Accumulating evidence suggests that the flavone glycoside baicalin has immunomodulatory effects and antitumor potential. However, its weak stability in solution, poor absorption, and low bioavailability limit its clinical application. To overcome these disadvantages, we developed baicalin-loaded poly(lactic-co-glycolic acid) nanoparticles (PLGA-B) of small size. Next, we evaluated the dual function of immunotherapy and chemotherapy for PLGA-B using immune-related cells and tumor cells. Results showed that PLGA-B were spherical, with a particle size similar to 120 nm and narrow size distribution with an excellent polydispersity index of 0.103. In vitro experiments revealed that baicalin and PLGA-B could activate dendritic cells (DCs) to have higher expression of surface marker molecules and costimulatory molecules than those of control cells. Baicalin and PLGA-B could trigger apoptosis in melanoma (B16) cells via cell-cycle arrest at the G2/M phase. These data suggest that PLGA-B have important roles in activating DCs and killing melanoma cells. Our study could lay a foundation for melanoma treatment through a combined strategy of immunotherapy and chemotherapy. (C) 2017 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.